Problem: $ { {5} \times \left[\begin{array}{rr}{-2} & {4} \\ {-1} & {0}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{5}\times{-2} & {5}\times{4} \\ {5}\times{-1} & {5}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-10} & {20} \\ {-5} & {0}\end{array}\right]}$